Dielectric Voltage Response in Spin-density Wave of (TMTSF) AsF at Low Temperature

Abstract
Voltage response to constant unipolar pulse current in the spin-density wave (SDW) state of (TMTSF) ₂AsF ₆ was studied. Below 3 K, leading and tailing edges of the voltage response are rounded at low electric field. The time dependent charge density accumulated in the lattice was estimated from the voltage profiles. It can be fitted by a stretched exponential formula; . With increasing field q₀ increases and shows a maximum at the threshold electric field for depinning. In the pinned state, the relaxation time increases with decreasing temperature and its activation energy is approximately equal to that of ohmic conductivity. The index is a linearly decreasing function of temperature and it is extrapolated to one at 0 K. Screening by normal carriers becomes imperfect and coupling between density wave domains becomes stronger on cooling.